The field of the present invention is that of devices for detecting a target by means of a trigger wire.
Such devices may be used in combination with a mine of the antipersonnel or anti-vehicle type.
Trigger wires are known which are placed on the ground by hand when the mine is laid.
These wires must be attached to a point remote from the mine so that they are in tension. Pulling or breaking the wire causes a firing pin to be released which detonates the explosive in the mine.
Patent FR2406180 describes such a device, Its principal disadvantage lies in requiring the trigger wires to be laid by hand, which prevents its dispersal by a shell, rocket or a launch system mounted on a vehicle.
Moreover the detonation device used with the wire is a complex and expensive mechanical system and cannot discriminate between different types of targets.
Trigger wires are also known which consist of flexible conductors designed to be broken by the target.
The break is detected by the electronics in the mine from the resulting change in electrical resistance of the wires.
The principal disadvantage of these wires is that they are fragile. Automatic deployment of the wires by pyrotechnic means (for example using the means described in patent FR2677750) is liable to break them, thus rendering the mine totally ineffective.
Finally trigger wires are known which consist of an optical fiber. Crushing of the said fiber modifies the light signal transmitted by the fiber and detonates the mine.
This approach is expensive. Moreover it involves substantial energy consumption because light muse be continuously transmitted through the fiber.
To limit this power consumption it is necessary to have recourse to a passive monitoring system (for example acoustic) which further complicates the detonation system of the mine.
This kind of trigger wire is usually reserved for antitank mines.